1. Field of the Invention
The present invention relates to a collision energy absorbable steering column of a vehicle, and more particularly to a collision energy absorbable steering column of a vehicle, which includes a wire block assembly that is fixed to a mounting bracket and that can absorb collision energy by wire deformation when a vehicle crashes against an object.
2. Description of the Prior Art
In general, a steering column refers to an apparatus, which encloses and supports a steering shaft that delivers rotatory force generated by a steering wheel operation of a driver to a rack-pinion mechanism, and is fixed to a chassis of a vehicle through a bracket, so as to fix a position of the steering shaft.
When a vehicle crashes against an object, the upper part of the driver's body hits against the steering wheel and is wounded. In order to prevent this, a collision energy absorbing steering column having a newly added collapse function that allows both the steering column and the steering shaft to be contracted in its shaft direction has been employed as a steering column. That is, when a driver is involved in a crashing accident during the driving, the upper part of the driver's body hits against the steering wheel due to inertia. When the upper part of the driver's body hits against the steering column, the steering column and the steering shaft provided on the lower part of the steering wheel are contracted so as to reduce the impact applied to the driver.
However, the collision energy transferred to the steering wheel due to the collision between the steering wheel and the driver depends on a driver state and a vehicle state. For example, large collision energy is transferred when the vehicle has a high speed, while small collision energy is transferred when the vehicle has a low speed. Further, the amount of collision energy applied to the steering wheel depends on several conditions such as the wearing of driver's seat belt, operation of an air bag, etc. A steering apparatus equipped with a tearing plate has been developed to cope with these conditions.
FIG. 1 is a side view showing a collision energy absorbable steering column of a vehicle according to the prior art. FIG. 2 is a perspective view showing a tearing plate of the collision energy absorbable steering column of the vehicle according to the prior art.
As shown in the drawings, the collision energy absorbable steering column of the vehicle 100 according to the prior art includes a steering shaft 102, an interior tube 110, an exterior tube 120, a mounting bracket 130, and a tearing plate 170. The steering shaft 102 has an upper end connected to a steering wheel (not shown), and a lower end connected to a rack-pinion mechanism (not shown). The interior tube 110 surrounds the steering shaft 102, and the exterior tube 120 surrounds the interior tube 110. The mounting bracket 130 is coupled to a chassis 104 through a capsule 140 while supporting an outer peripheral surface of the exterior tube 120. The tearing plate 170 has one end fixed to the capsule 140 by a fixing means 150 and the other end fixed to the mounting bracket 130 through a fixing member 160.
When the upper part of driver's body collides with the steering wheel due to a frontal crashing of a vehicle, the steering column 100 is contracted in the direction (i.e. a collision energy transfer direction or a collapse direction) in which the impact has been applied to the steering wheel. Then, the mounting bracket 130 moves together with the exterior tube 120 in the collapse direction from the capsule 140 fixed on the chassis 104. That is, when the collision occurs, the mounting bracket 130 is separated from the capsule 140, is easily released from the chassis 104, and then moves in the collapse direction (i.e. in the collision energy transfer direction), while the steering column 100 is contracted.
The tearing plate 170 of the collision energy absorbing steering column according to the prior art has a fixing hole 202 formed through a top portion of one side of the tearing plate 170 and an assembling hole 204 formed through another portion thereof. The tearing plate 170 is assembled with the mounting bracket 130 by a fixing member 160 fitted in the fixing hole 202, and is assembled with the capsule 140 by the fixing means 150 fitted in the assembling hole 204. The tearing plate 170 is provided with a tearing groove 210 with a uniform depth.
According to the contraction of the steering column, the mounting bracket 130 moves against the capsule 140, and the mounting bracket 130 moves downward. Then, force from the capsule 140 and force from the mounting bracket 130 are applied to the tearing plate 170 in opposite directions. As a result, the tearing plate 170 is torn along the tearing groove 210 formed on the tearing plate 170 according to the movement of the mounting bracket 130 while absorbing the collision energy. That is, the fixing member 160 formed on the mounting bracket 130 absorbs the collision energy while deforming the tearing plate 170.
However, in the case of absorbing the collision energy by the breaking of the tearing plate along the tearing groove 210 having a uniform depth as described above, it is impossible to cope with various quantities of impact according to various situations and impossible to control the magnitude of an initial load against impact. Moreover, the deformation occurs only in a perpendicular direction and may cause interference between the torn part and surrounding objects, which may cause biased deformation or biased damage.